. Dental shorter pin makes the leveragein favor of the crown, and the root is liable to be split. Giveall the advantage to the root, since by this method it canbe so easily done, and docs not add disadvantages. Do so,as another crown can be made, but a split root is a seriousproblem. In bridge work, strain against the root is stillfurther increased, and extra length of pin means extra 814 THE DENTAL SUMMARY strength, making the whole root bear the force instead ofputting it on the part of the root at the gum line. An eighthof an inch more pin length adds as as any band.
. Dental shorter pin makes the leveragein favor of the crown, and the root is liable to be split. Giveall the advantage to the root, since by this method it canbe so easily done, and docs not add disadvantages. Do so,as another crown can be made, but a split root is a seriousproblem. In bridge work, strain against the root is stillfurther increased, and extra length of pin means extra 814 THE DENTAL SUMMARY strength, making the whole root bear the force instead ofputting it on the part of the root at the gum line. An eighthof an inch more pin length adds as as any band. The plate should be of gold, 24k, 34 gauge, because itis easy to adapt and forms no blue line at joint, as doesplatinum. Your attention is called to Fig. 5. This is a pieceof board with three bolts of equal size screwed into it. are of regularly increasing length. Bolt A is the short-est and is simply screwed into the board. Bolt B is alsoscrewed in and. has a nut screwed against the board. Bolt C Fig. 5. ABC is not only screwed in, but has a washer against the board anda nut screwed down upon it. It takes very little pressureagainst A to split the board. B is longer than A, and there-fore the leverage in its favor is greater, but in spite of this,more force is required to split ,-the board than was used on nut overcame the increased leverage. For C, the longestbolt, decidedly more force is required. In fact, when thewasher is of the same size as the width of the board (as existsin the mouth) the tendency is for the wood to twist in tworather than split. In the mouth no such exaggeration of lever- THE DENTAL SUMMARY 315 age exists. This experiment and experience prove that wherewe have a long pin of ample size, and a plate over the rootend, we have all the strength necessary, and bands are simplyuseless encumbrances. Sloping the root, as is usually done,still further increases the strength, by taking the force offthe front half of the root and transferring it t
Size: 1624px × 1539px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookiddent, booksubjectdentistry
